1. Field of the Invention
The present invention generally relates to deposition apparatuses, substrate process apparatuses, film deposition methods, and computer readable storage media. More specifically, the present invention relates to a film deposition apparatus, a substrate process apparatus and a film deposition method for depositing a film on a substrate by repeatedly carrying out cycles of supplying in turn at least two source gases to the substrate in order to form a layer of a reaction product, and a computer readable storage medium storing a computer program for causing the film deposition apparatus to carry out the film deposition method.
2. Description of the Related Art
As a film deposition technique in a semiconductor manufacturing process, there is known a so-called Atomic Layer Deposition (ALD) or Molecular Layer Deposition (MLD). In such a film deposition technique, a first reaction gas is adsorbed on a surface of a semiconductor wafer (hereinafter a “wafer”) under a vacuum environment and then a second reaction gas is adsorbed on the surface of the wafer in order to form one or more atomic or molecular layers through reaction of the first and the second reaction gases on the surface of the wafer; and such an alternating adsorption of the gases is repeated plural times, thereby depositing a film on the wafer. This technique is advantageous in that the film thickness can be controlled at higher accuracy by the number of times alternately supplying the gases, and in that the deposited film can have excellent uniformity over the wafer. Therefore, this deposition method is thought to be promising as a film deposition technique that can address further miniaturization of semiconductor devices.
Such a film deposition method may be preferably used, for example, for depositing a dielectric material to be used as a gate insulator. When silicon dioxide (SiO2) is deposited as the gate insulator, a bis (tertiary-butylamino) silane (BTBAS) gas or the like is used as a first reaction gas (source gas) and ozone gas or the like is used as a second gas (oxidation gas).
In order to carry out such a deposition method, use of a single-wafer deposition apparatus having a vacuum chamber and a shower head at a top center part of the vacuum chamber has been under consideration. In such a deposition apparatus, the reaction gases are introduced into the chamber from the top center part, and unreacted gases and by-products are evacuated from a bottom part of the chamber. When such a deposition chamber is used, it takes a long time for a purge gas to purge the reaction gases, resulting in an extremely long process time because the number of cycles may reach several hundred. Therefore, a deposition method and an apparatus that enable high throughput are desired.
Under these circumstances, film deposition apparatuses having a vacuum chamber and a rotation table that holds plural wafers along a rotational direction have been proposed.
Patent Document 1 describes the following structure. A flattened cylindrical-shaped vacuum chamber is divided into a left side area and a right side area. Evacuation openings are formed along outlines of semicircles at the left side area and the right side area for upward evacuation. An eject opening of separation gas is formed between the outline of the left side semicircle and the outline of the right side semicircle, namely a diameter area of the vacuum chamber. A supply area of a different material gas is formed in each of a right side semicircle area and a left side semicircle area. By rotating a rotation table in the vacuum chamber, a work piece passes through the right side semicircle area, the separation area D, and the left side semicircle area and the material gases are evacuated from the evacuation opening.
Patent Document 2 describes a process chamber having a wafer support member (rotation table) that holds plural wafers and that is horizontally rotatable, first and second gas ejection nozzles that are located at equal angular intervals along the rotation direction of the wafer support member and oppose the wafer support member, and purge nozzles that are located between the first and the second gas ejection nozzles. The gas ejection nozzles extend in a radial direction of the wafer support member. A top surface of the wafers is higher than a top surface of the wafer support member, and the distance between the ejection nozzles and the wafers on the wafer support member is about 0.1 mm or more. A vacuum evacuation apparatus is connected to a part between the outer edge of the wafer support member and the inner wall of the process chamber. According to a process chamber so configured, the purge gas nozzles discharge purge gases to create a gas curtain, thereby preventing the first reaction gas and the second reaction gas from being mixed.
Patent Document 3 describes a process chamber that is divided into plural process areas along the circumferential direction by plural partitions. Below the partitions, a circular rotatable susceptor on which plural wafers are placed is provided leaving a slight gap in relation to the partitions.
Patent Document 4 describes a structure where a circular-shaped gas supply plate is divided into eight parts in a circumferential direction. A supply opening of AsH2 gas, a supply opening of H2 gas, a supply opening of TMG gas, and a supply opening of H2 gas are arranged with gaps of 90 degrees. In addition, evacuation openings are provided between neighboring gas openings. A susceptor configured to support a wafer and facing these gas supply openings is rotated.
Patent Document 5 describes a process chamber having a circular plate that is divided into four quarters by partition walls and has four susceptors respectively provided in the four quarters, four injector pipes connected into a cross shape, and two evacuation ports located near the corresponding susceptors. In this process chamber, four wafers are mounted in the corresponding four susceptors, and the four injector pipes rotate around the center of the cross shape above the circular plate while ejecting a source gas, a purge gas, a reaction gas, and another purge gas, respectively.
Furthermore, Patent Document 6 (Patent Documents 7, 8) describes a film deposition apparatus preferably used for an Atomic Layer CVD method that causes plural gases to be alternately adsorbed on a target (a wafer). In the apparatus, a susceptor that holds the wafer is rotated, while source gases and purge gases are supplied to the susceptor from above. Paragraphs 0023, 0024, and 0025 of the document describe partition walls that extend in a radial direction from the center of a chamber, and gas ejection holes that are formed in the bottom of the partition walls in order to supply the source gases or the purge gas to the susceptor, so that an inert gas as the purge gas ejected from the gas ejection holes produces a gas curtain. Regarding evacuation of the gases, paragraph 0058 of the document describes that the source gases are evacuated through an evacuation channel 30a, and the purge gases are evacuated through an evacuation channel 30b. With such a configuration, the source gases can flow into a purge gas compartment from source gas compartments located on both sides of the purge gas compartment and the gases can be mixed with each other in the purge gas compartment. As a result, a reaction product is generated in the purge gas compartment, which may cause particles to fall onto the wafer.    [Patent Document 1] U.S. Pat. No. 7,153,542 (FIGS. 6A, 6B)    [Patent Document 2] Japanese Patent Application Laid-Open Publication No. 2001-254181 (FIGS. 1, 2)    [Patent Document 3] Japanese Patent Publication No. 3,144,664 (FIGS. 1, 2, claim 1)    [Patent Document 4] Japanese Patent Application Laid-Open Publication No. H4-287912    [Patent Document 5] U.S. Pat. No. 6,634,314    [Patent Document 6] Japanese Patent Application Laid-Open Publication No. 2007-247066 (paragraphs 0023 through 0025, 0058, FIGS. 12 and 13)    [Patent Document 7] U.S. Patent Publication No. 2007-213701    [Patent Document 8] U.S. Patent Publication No. 2007-218702
However, in the apparatus described in Patent Document 1, the upward evacuation openings are formed between the eject opening of the separation gas and the supply area of the reaction gas. In addition, the reaction gas is evacuated with the separation gas from the evacuation openings. Accordingly, the reaction gas ejected toward the work piece is drawn in from the evacuation openings as an upward flow so that particles in the chamber may be blown upward by the upward flow of the gases and fall on the wafers, leading to contamination of the wafers.
In addition, in the technique described in Patent Document 2, the wafer support member is rotated. Accordingly, it is not possible to prevent the reaction gas at both sides of the purge gas nozzle from passing by only the air curtain action from the purge gas nozzle. Hence, it is not possible to avoid the reaction gas being diffused in the air curtain from an upstream side in the rotational direction. Furthermore, the first reaction gas ejected from the first reaction gas ejecting nozzle easily reaches the second reaction gas diffusion area via a center part of the wafer support member corresponding to the rotation table. Once the first and second reaction gases are mixed on the wafer, an MLD (or ALD) mode film deposition cannot be carried out because the reaction product is adhered to a surface of the wafer.
In addition, in the technique described in Patent Document 3, the process gas is diffused to a neighboring process chamber from a gap between the partition and the susceptor. Furthermore, an evacuation room is provided among plural process chambers. Hence, when the wafer passes through the evacuation room, a gas from the process chamber at an upstream side and a gas from the process chamber at a downstream side are mixed. Because of this, this structure cannot be applied to the ALD type film deposition method.
In addition, Patent Document 4 does not provide any realistic measures to prevent two source gases (AsH3, TMG) from being mixed. Because of the lack of such measures, the two source gases may be mixed around the center of the susceptor and through the H2 gas supplying plates. Moreover, because the evacuation ports are located between the adjacent two gas supplying plates to evacuate the gases upward, particles are blown upward from the susceptor surface, which leads to wafer contamination.
In addition, in the technique described in Patent Document 5, after the source gas or the reaction gas is supplied to each of the four quarters, an atmosphere of each of the four quarters is displaced by purge gas by using the purge nozzle, which takes a long time. Furthermore, the source gas or the reaction gas is diffused from one of the four quarters to the neighboring ones of the four quarters beyond vertical walls. Hence, both gases may be reacted in the four quarters.